To the Editor.—In an article by Hart and Sherman (1982;247:498), the diagnostic procedures useful in multiple sclerosis (MS) were described. They pointed out that the oligoclonal banding (OCB) seen on agarose gel electrophoresis is regarded as the most sensitive marker of MS, being present in 85% to 95% of MS cases. As they note, however, OCB can be seen in a variety of chronic infectious and inflammatory diseases of the nervous system. We believe the latter observation warrants additional emphasis. We have recently seen two patients (women aged 26 and 44 years) who experienced acute, severe visual loss caused by autoimmune vasculitis and who had increased CSF IgG levels, with positive test results for OCB.

Report of Cases.—Case 1.—The first patient experienced retrobulbar optic neuritis (RON) with a decrease in vision to light perception in the right eye, with a normal disc and retina. This episode responded to